By default, after installing Varnish you may notice that the client IP address listed in the Apache log files is 127.0.0.1. If you have configured Varnish to listen for traffic on port 80 and forward all non-cached traffic onto Apache. Apache sees this a local request so the IP address will appear to be 127.0.0.1. This can prove to be annoying when debugging your site or if you ever have the need to block requests made by a particular IP address. To solve this problem we will need to enable vcl_rev in our default.vcl file and configure it to forward the client IP address. Then we will need to configure apache to support a new LogFormat, and then we will need to modify our virtual hosts to support the new format. This tutorial assumes that you already have Varnish configured with Apache and it is working as expected.